The present invention relates to a two dimensional drive system, more precisely relates to a two dimensional drive system which is capable of moving a slider in a plane.
There is disclosed a conventional drive system, which is capable of moving a slider in a plane, in Japanese Patent Kokai Gazette No. 59-232778. The drive system has a pair of X-axis guides provided in an X-direction; a pair of Y-axis guides provided in a Y-direction perpendicular to the X-direction; a pair of X-travellers slidably engaged with each X-travellers; a pair of Y-travellers slidably engaged with each Y-travellers; an X-ball bearing screw rotatably spanned between the Y-travellers; a Y-ball bearing screw rotatably spanned between the X-travellers; a slider to which the X- and Y-ball bearing screws are screwed whereby the slider is capable of moving on the X- and Y-ball bearing screws with the rotation thereof; and motors for driving the X- and Y-ball bearing screws.
However, the conventional two dimensional drive system has a following disadvantages:
The X- and Y-travellers are merely slidably engaged with the X- and Y-guides. Therefore, when the slider, which is close to one of the X-travellers, moves in the X-direction, the other X-traveller moves later than the one thereof, so that the Y-ball bearing screw is inclined with respect to the Y-axis; when the slider, which is close to one of the Y-travellers, moves in the Y-direction, the other Y-traveller moves later than the one thereof, so that the X-ball bearing screw is inclined with respect to the X-axis. By inclination of the X- and Y-ball bearing screws, the positioning accuracy of the slider may be quite low, and the vibration of the slider may be caused during high speed operation.